Anti-clogging device for diesel exhaust fluid supply

ABSTRACT

An apparatus for supplying Diesel Exhaust Fluid to an engine exhaust gas treatment system includes a reservoir to collect trapped air if the dosing module is clogged with crystalized urea. The reservoir is placed at the dosing valve inlet on a T-connection. The reservoir provides a closed chamber to receive trapped air in the DEF supply line, allowing DEF to flow to the dosing module. When DEF contacts the crystallized urea causing the clog, the urea dissolves, freeing the injector so that normal action of the dosing module is restored.

FIELD OF THE INVENTION

The invention relates to Diesel Exhaust Fluid dosing apparatuses for vehicles, and more particularly to a device for alleviating clogging of the dosing apparatus.

BACKGROUND AND SUMMARY

Diesel Exhaust Fluid (DEF), commonly referred to as AdBlue in Europe, is an aqueous urea solution of 32.5% high-purity urea and 67.5% deionized water. DEF is consumed as a reactant in selective catalytic reduction (SCR) systems to lower the NOx content in the diesel exhaust emissions from diesel engines.

DEF is typically carried on the vehicle in a supply tank and a dosing apparatus draws DEF from the tank and injects it into the exhaust upstream of an SCR catalyst. The urea is converted via thermolysis and hydrolysis into ammonia. Inside the SCR catalyst body, the ammonia then reduces the nitrogen oxides (NOx) into water and nitrogen.

A dosing apparatus, in addition to the supply tank, will typically include a supply module having a pump and a dosing module including a valve and injector.

Under certain conditions, in particular with exposure of DEF in the dosing module to exhaust gas heat, urea can crystallize out of the DEF solution and collect in the dosing module components, which can prevent free movement of the injector. Crystallized urea will rapidly dissolve on contact with DEF; however, when the injector is stuck, air in the supply line becomes a pressurized pocket that prevents DEF from flowing to the dosing module.

One solution known in the art is a dosing valve having a return line for continuous flow of DEF through the dosing module.

The invention proposes a solution to the clogging problem.

According to the invention, a reservoir is placed at the dosing valve inlet on a T-connection. The reservoir provides a closed chamber to receive trapped air in the DEF supply line, allowing DEF to flow to the dosing module. When DEF contacts the crystallized urea causing the clog, the urea dissolves, freeing the injector so that normal action of the dosing module is restored.

BRIEF DESCRIPTION OF THE DRAWING

The sole Figure is a schematic view of an apparatus according to the invention.

DETAILED DESCRIPTION

The appended Figure shows a schematic view of a DEF dosing apparatus according to the invention.

The apparatus includes a DEF supply tank 10, a pump (or supply module) 20, and a dosing module 30. A supply line 15 connects the pump inlet 22 to the supply tank 10. A feed line 24 connects the pump outlet 26 to a T connector 40.

The T connector 40 has an inlet 42 to receive DEF from the pump 20, a first outlet 44 to deliver DEF to the dosing module 30 and a second outlet 46 connecting to a reservoir 50. The reservoir 50 is a closed chamber, which may be a capped pipe, for example, or another vessel that can be connected in fluid communication with the line between the pump and dosing module to accept air that would otherwise be trapped in the line between the pump and the dosing module if urea has crystallized in the dosing module. By providing a chamber for the air trapped in the line, the apparatus facilitates the flow of DEF even when crystallized urea might cause a blockage.

The reservoir 50 may be placed vertically above the dosing module 30.

When DEF flows to and contacts the crystallized urea, the crystallized urea dissolves, freeing the dosing injector.

In the present application, the use of terms such as “including” is open-ended and is intended to have the same meaning as terms such as “comprising” and not preclude the presence of other structure, material, or acts. Similarly, though the use of terms such as “can” or “may” is intended to be open-ended and to reflect that structure, material, or acts are not necessary, the failure to use such terms is not intended to reflect that structure, material, or acts are essential. To the extent that structure, material, or acts are presently considered to be essential, they are identified as such.

While this invention has been illustrated and described in accordance with a preferred embodiment, it is recognized that variations and changes may be made therein without departing from the invention as set forth in the claims. 

1. An apparatus for delivering aqueous urea fluid into an exhaust gas system of a combustion engine, comprising: a dosing module mountable on an engine exhaust conduit and configured to deliver aqueous urea fluid to the exhaust conduit; a feed line connected to carry aqueous urea fluid to an inlet of the dosing module; and, a reservoir for collecting air trapped in the feed line connected to the feed line at the inlet of the dosing module, wherein the feed line includes a branch at the inlet of the dosing module, the reservoir connected to the branch.
 2. The apparatus of claim 1, comprising a pump connected on the feed line to deliver aqueous urea fluid to the feed line.
 3. The apparatus of claim 2, comprising an aqueous urea fluid supply tank and a supply line connecting the supply tank to the pump.
 4. The apparatus of claim 1, wherein the reservoir is vertically above the dosing module.
 5. An apparatus for delivering aqueous urea fluid to an exhaust gas system of a combustion engine, comprising: a supply tank 10 for storing aqueous urea fluid; a pump 20 having an inlet and an outlet, the inlet connected by a supply line to the supply tank; a dosing module 30; a feed line 24 connecting the pump outlet 26 to the dosing module, the feed line having a T-connector at the dosing module, the T connector 40 having an inlet 42 to receive DEF from the pump 20, a first outlet 44 to deliver DEF to the dosing module 30, and a second outlet 46; a reservoir 50 connected to the second outlet to collect air trapped at an inlet of the dosing module.
 6. The apparatus of claim 5, wherein the reservoir 50 is a closed chamber having a single opening, the single opening connected at the second outlet.
 7. An apparatus for delivering aqueous urea fluid into an exhaust gas system of a combustion engine, comprising: a dosing module mountable on an engine exhaust conduit and configured to deliver aqueous urea fluid to the exhaust conduit; a pump to deliver aqueous urea fluid to the dosing module; a feed line having a first end connected to an outlet of the pump and a second end having two branches, a first branch connected to an inlet of the dosing module; and, a reservoir on the second branch of the feed line, the reservoir for collecting air trapped in the feed line.
 8. The apparatus of claim 7, wherein the reservoir is a closed chamber having a single opening. 